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Re: bug#45596: 12.2.4; Wrong DPI calculation for mixed-DPI multi-monitor
Re: bug#45596: 12.2.4; Wrong DPI calculation for mixed-DPI multi-monitor setups
Sun, 26 Jun 2022 18:35:28 +0900
Hi Tassilo, can I expect you to take care of this issue?
(And in addition to bug#20171, I hope bug#25002 and bug#27213 can be
closed as well:
>>>>> Ikumi Keita <email@example.com> writes:
>>>>> Tassilo Horn <firstname.lastname@example.org> writes:
>> Grzegorz Kowzan <email@example.com> writes:
>> Hi Grzegorz,
>>>> I guess the problem is that mm-size in the `frame-monitor-attributes'
>>>> return value differs from `display-mm-height' and `display-mm-width'.
>>> 1) Yes, `display-pixel/mm-width/height` functions are defined in terms
>>> of Xlib calls, whereas `frame-monitor-attributes` calls Gdk functions
>>> (if Emacs was compiled with Gtk support) and only as a fallback it
>>> calls Xlib. This is why we have this inconsistency. The standard DPI
>>> for Xorg server is 96 regardless of the actual value, so for a given
>>> resolution and assumed DPI Xorg gives fake mm width and
>>> height. Essentially, the current calculation of DPI in auctex looks
>>> pointless to me...
>> Ok, I see.
>>> With pure Gtk port we get actual physical pixel width/height and
>>> actual mm width/height, so I guess when auctex detects pgtk port, it
>>> can either ignore these values and hardcode DPI of 96 or make use of
>>> the actual DPI. I suppose there is something to be said for not
>>> changing auctex's behaviour and hardcoding the value, but I would
>>> prefer to use the actual DPI at least as an option (see below).
>> That's what I did. Essentially I've applied your patch with an
>> additional fboundp check for `frame-monitor-attributes'. If it's
>> available (24.4), then your variant is used, if not, the previous
>> variant basically always saying 96 DPI is used.
> Isn't it a good time to carry out this TODO in preview.el.in? ;-)
> | (defun preview-get-dpi ()
> | ;; TODO: Remove false-case when required emacs version is bumped to
> | ;; 24.4 or newer as this is the version where
> | ;; `frame-monitor-attributes' has been introduced.
> | (if (fboundp 'frame-monitor-attributes)
> | (let* ((monitor-attrs (frame-monitor-attributes))
> | (mm-dims (cdr (assoc 'mm-size monitor-attrs)))
> | (mm-width (nth 0 mm-dims))
> | (mm-height (nth 1 mm-dims))
> | (pixel-dims (cdddr (assoc 'geometry monitor-attrs)))
> | (pixel-width (nth 0 pixel-dims))
> | (pixel-height (nth 1 pixel-dims)))
> | (cons (/ (* 25.4 pixel-width) mm-width)
> | (/ (* 25.4 pixel-height) mm-height)))
> | (cons (/ (* 25.4 (display-pixel-width))
> | (display-mm-width))
> | (/ (* 25.4 (display-pixel-height))
> | (display-mm-height)))))
> And I'd like to comment on two minor aspects.
> 1. The function `cdddr' used above isn't yet available for emacs 25.1,
> so it should be replaced with `cl-cdddr'. I noticed this thanks to a
> byte compile log which Michael Braun sent me off list. Thank you,
> Michael! (And this means that preview-latex didn't work at all for
> emacs 25.1 for this 1.5 years!)
> 2. Though bug#20171 is still open, I hope it has already been
> resolved as well with this bug#45596. If so, let's close it, too.
> Ikumi Keita
> #StandWithUkraine #StopWarInUkraine
>  https://debbugs.gnu.org/cgi/bugreport.cgi?bug=20171